1. Field of the Invention
The invention relates in general to waterproof audio systems, and, in particular, to headphones for such systems. The system is submersible and is particularly well suited for use while swimming or snorkeling.
2. Description of the Prior Art
Waterproof cassette players and associated headphones had been previously proposed. See, for example, Silverman U.S. Pat. No. 4,683,587. Silverman describes a submersible personal stereo. Silverman's disclosed system includes an electro-acoustical transducer coupled to a small internal diameter acoustic transmissive tube. The tubing is hydrophilic and of small enough diameter to prevent water from entering. The speaker is a dynamic speaker. This system tended to take in water when accidentally dislodged from the ear at depths of several feet under water.
The use of hydrophobic materials in a membrane of an ear plug to block the passage of water up to a predetermined pressure while permitting the passage of air and sound is proposed by Adams U.S. Pat. No. 5,488,961.
The use of a single piezoelectric speaker with a plurality of acoustic leads to separate ear pieces is disclosed by Kenning et al. U.S. Pat. No. 5,600,730. The proposed arrangement leaves the system vulnerable to the influx of water because water entering one acoustic lead displaces the air out through the other lead. This is a serious drawback to the use of the proposed structure.
Bipolar armature transducers have been widely used in hearing aids, and their design is well known to those skilled in the art.
These and other difficulties of the prior art have been overcome according to the present invention.